Although it shook the band's fan base to its core, the acrimonious departure of vocalist Ian Gillan and bassist Roger Glover served to rejuvenate Deep Purple in time for 1973's aptly named Burn album, which unquestionably showed huge improvement over their lackluster previous effort, Who Do We Think We Are.

And in an interesting twist rarely attempted before or since, new recruits David Coverdale (vocals) and Glenn Hughes (bass and vocals, ex-Trapeze) traded lead singing duties on virtually every one of its songs -- an enviable tag team, as both possessed exceptional pipes.

The phenomenal title track started things off at full throttle, actually challenging the seminal "Highway Star" for the honor of best opener to any Deep Purple album, while showcasing the always impressive drumming of Ian Paice.

Up next, the intro to the equally timeless "Might Just Take Your Life," however simple from a technical perspective, remains one of organist Jon Lord's signature moments; and the downright nasty "Lay Down, Stay Down" roared behind wildly careening starts and stops and a fantastic Ritchie Blackmore guitar solo which left no doubt as to who was the band's primal force, regardless of lineup.

Moving right along, though it was rarely included in later-day greatest hits sets, "What's Going on Here" was about as good a single as Purple ever wrote; "You Fool No One" was compelling for its sheer intensity; and the funky "Sail Away" was a sign of the band's direction in years to come.

Lastly, the fantastic slow-boiling blues of "Mistreated" closed the album proper (let's ignore the record's only throw-away track -- boring final instrumental "A 200") with a command solo performance from Coverdale, as nuanced and sensitive as it was devastating.

So impassioned was the singer's delivery, in fact, that the song would remain his personal, in-concert trademark with Whitesnake, long after his tenure with Deep Purple came to a close.

Like the vast majority of Burn this song's greatness qualifies it for the highest echelons of hard rock achievement, and therefore ranks as an essential item in the discography of any self-respecting music fan.